The present invention relates to a data embedding technique for embedding an objective data to be embedded in data, and a data extraction technique for extracting an objective data to be embedded from data.
For example, the present invention relates in general to a digital voice (speech) signal processing technique including packet voice communication or digital voice storage as an application field with the explosive growth of the Internet in the background. More particularly, the invention relates to a data embedding technique for replacing a part of digital codes compressed by utilizing a speech encoding technique with arbitrary data without deteriorating voice quality while holding conformity to the standard of a data format.
In recent years, while computers and the Internet become widespread, “a digital watermarking technique” for embedding a special data in multi-media contents (such as a still picture, a moving picture, an audio, or a voice) has attracted public attraction. Such a technique, for the purpose of mainly protecting a copyright, is used to embed a name of a producer, a salesperson or the like in contents in order to prevent unlawful copy or revision of data. In addition thereto, such a technique is used for the purpose of embedding related information or additional information concerned with contents in order to enhance convenience during utilization of contents by a user.
In a field of voice communication as well, there is made an attempt to embed such arbitrary information in a voice to transmit or store the resultant information. A conceptual diagram is shown in FIG. 1. In FIG. 1, an encoder, when encoding an input voice into a speech code (voice code), embeds an arbitrary data sequence other than a voice in a speech code to transmit the resultant code to a decoder. At this time, the data is embedded in the speech code itself without changing a format of the speech code. For this reason, a quantity of information of the speech code is not increased. The decoder reads out the embedded arbitrary data sequence from the speech code, and outputs a regenerative voice after a normal processing for decoding a speech code has been executed.
With in the above-mentioned configuration, it becomes possible to transmit arbitrary data in addition to a voice without increasing a transmission quantity. In addition, a third person that is not aware of that the data is embedded merely recognizes the communication concerned as normal voice (speech) communication. As for a method including embedding data, various kinds of methods have been proposed.
As for the prior art concerned with the present invention, for example, there are techniques disclosed in the following patent documents 1 to 4. The patent document 1 is “JP 2003-99077 A”, the patent document 2 is “JP 2002-521739 A”, the patent document 3 is “JP 2002-258881 A”, and the patent document 4 is “WO 00/039175”.
In the above-mentioned technique for embedding and extracting data in and from a speech code, it is desirable to embed much data in a speech code. In addition, it is also desirable that a voice quality is not degraded due to the embedding of data. Moreover, it is desirable that accurate embedded data is obtained on a decoding side.
It is one of objects of the present invention to provide a technique that is capable of increasing a transmission capacity of embedded data.
In addition, it is one of objects of the present invention to provide a technique that is capable of suppressing generation of voice quality degradation due to embedding of data.
Furthermore, it is one of objects of the present invention to provide a technique that is capable of obtaining accurate embedded data on a side of reception of data.